The present invention relates to a method and a device for synthetic generation of an acoustic signal, e.g. in a vehicle. A control signal for controlling a motor or a detection signal, which detects the engine speed for example, is fed as input signal to a device for generating the acoustic signal, wherein at least one electromechanical transducer generates the acoustic signal by means of an electrical transducer excitation signal. To this end, an electromechanical transducer can be a loudspeaker or an exciter which generates sound waves at components of a vehicle.
The present invention relates to a method and a device for synthetic generation of an acoustic signal, e.g. in a vehicle. A control signal for controlling a motor or a detection signal, which detects the engine speed for example, is fed as input signal to a device for generating the acoustic signal, wherein at least one electromechanical transducer generates the acoustic signal by means of an electrical transducer excitation signal. To this end, an electromechanical transducer can be a loudspeaker or an exciter which generates sound waves at components of a vehicle.
It is already well known to artificially generate engine sounds of an internal combustion engine or engine in general in a motor vehicle or to amplify the engine sounds of an internal combustion engine through various devices and methods and to change their tone in a particular manner. This is often accomplished using a particular structural design of the components of the engine or exhaust gas system, wherein it is moreover also possible to integrate electromechanical transducers (exciters or loudspeakers) in the exhaust gas system of a motor vehicle having an internal combustion engine for example in order to adapt the sound waves naturally generated by the internal combustion engine to a desired sound through sound waves generated by the exciter or loudspeaker.
It is furthermore well known to equip electric vehicles or hybrid vehicles that can often be operated only by means of an electric motor or also in electric mode with a sound that resembles that of an internal combustion engine. On the one hand, this should increase the purchase and acceptance of these types of vehicles by customers and also increase safety for other road users, such as pedestrians or bicyclists, who are accustomed to motor vehicles having a typical engine sound which thereby also warns them about this motor vehicle (e.g. when crossing a street).
However, the difficulty lies in generating an engine sound that sounds as natural as possible and corresponds to the engine sound of a conventional motor vehicle having an internal combustion engine without sounding monotone. Devices known in the art for generating artificial engine sounds often sound synthetic.
A method for synthetic generation of engine sounds, especially of an internal combustion engine, in which a sequence of successively generated signal sequence sections of particular sequence time intervals form a transducer excitation signal is known from DE 10 2007 055 477 A1. To this end, the engine sounds are formed from the transducer excitation signal. A sequence of successively generated signal sequence sections having particular sequence time intervals form the transducer excitation signal, wherein each signal sequence section consists of successive signal segments as signal oscillations of particular sequence time intervals, and wherein the sum of the sequence time intervals of the signal segments contained in a signal sequence section determines the sequence time interval of the assigned signal sequence section and at least two signal segments in a signal sequence section are unequal in regard to their segment time intervals and/or segment amplitudes. In the method described in DE 10 2007 055 477 A1, the transducer excitation signal is nevertheless calculated as a function of the number of cylinders of an internal combustion engine to be imitated.
DE 10 2005 012 463 B3 describes a method for generating an engine sound of a motor vehicle having an additional sound generated by an actuator and a device for carrying out the method, wherein in a data memory of a control unit for the generation, there is stored an engine characteristic map in which level values evaluated through boundary conditions are stored at engine speed nodes, these level values being stored as multiples of half the engine speed for defined engine speeds and their assigned oscillations and orders. The stored level values corresponding to the current speed signal and therefore to the current engine speed and its higher orders are then read from the data memory and transmitted to an arithmetic unit of the control unit, wherein an actuator excitation signal as a continuous time signal in the manner of a harmonic series is calculated from the level values and the actuator excitation signal is formed therefrom. The actuator excitation signal is then outputted via a power amplifier to the actuator as an electric actuator signal, wherein the actuator converts the electric actuator signal into a vibratory force in the manner of an electrodynamic vibrator.
DE 10 2010 043 973 A1 discloses the generation of a sound for a motor vehicle driven by an electric motor, wherein a control signal for an electric motor or for the electric motor's power electronics is generated, the control signal having a modulation for sound generation and the control signal controlling the electric motor, wherein the modulation in the electric motor generates vibrations which produce the sound.
Furthermore known from the state of the art are methods and devices in which, proceeding from a vehicle-specific parameter (rotary frequency, speed, engaged gear, etc.), a sound assigned to this operating state is read from a memory and outputted through a loudspeaker or exciter.
A disadvantage of the methods and devices known from the state of the art, however, is that they cannot approximately generate the natural sound of an internal combustion engine, above all because they generate strictly periodic signals and sounds or generate signals and sounds that have repeating components. This also applies to DE 10 2007 055 477 A1, which indeed makes use of different segment time intervals and/or segment amplitudes for two signal segments within one signal sequence section, but severely limits the number of signal sequence sections and number of signal segments in the signal sequence sections, thereby again producing very artificially sounding sounds.
It is therefore the objective of the present invention to present a method and a device in which an acoustic signal is synthetically generated, wherein the generated acoustic signal is to sound very natural and no complex calculations need to be made.
The objective is accomplished by a method having the characteristics stated herein and by a device having the characteristics stated herein.
Advantageous modifications are disclosed in detail in the claims.